The periodontium is the tissue that surrounds and supports teeth, consisting of the gingiva, periodontal membrane, cementum, and alveolar bone. Among periodontal inflammations, inflammation limited to the gingiva is called “gingivitis,” and inflammation whose lesion spreads beyond the gingiva to damage and destroy the periodontal membrane and alveolar bone is called “periodontitis.”
Both gingivitis and periodontitis are periodontal inflammations caused by bacterial growth in plaque (intraoral mass of food residue and others, where bacteria adhere and grow) and other factors. However, in the case of gingivitis, gingival inflammation does not spread to the periodontal membrane and alveolar bone and thus can be treated by intraoral cleaning, but when gingivitis advances to periodontitis, a tooth becomes loose, and the periodontal membrane and alveolar bone are damaged and destroyed, with resulting difficulties in fixation even though intraoral cleaning is carried out.
Diagnosis of periodontal diseases is generally conducted by measurement of a periodontal pocket, attachment level, X-ray diagnosis, and others. A “periodontal pocket” is a crevice (a gingival crevice) between the tooth and gingiva, caused by gingival detachment from tooth due to gingivitis or periodontitis; thus, the severity of destruction of the periodontium can be known to some extent by measuring the depth of a periodontal pocket. “Attachment level” is a distance from the boundary between the cementum and enamel to the bottom of a periodontal pocket, an indicator to know the severity of the destruction of periodontal supporting tissue. In “X-ray diagnosis,” absorption of the alveolar bone and others can be observed by radiography.
Several diagnostic methods of periodontal diseases using measurement of various enzymes contained in the fluid leaked out into the said gingival crevice (gingival crevicular fluid) during gingivitis and periodontitis have been proposed. For example, a diagnostic method of periodontal diseases, which measures peroxidase activity elevated along with increased leukocytes during inflammation, has been disclosed (patent document 1).
In addition, a diagnostic method of periodontal diseases, which measures ALT (alanine aminotransferase) concentration that is increased in gingival crevicular fluid due to periodontal inflammation and damage, has been disclosed (patent document 2).
Also, there is prior literature concerning an objective diagnostic method of the advancement stages of periodontal diseases by specifically detecting ALP (alkaline phosphatase) enzymes released by pathogenic bacteria of periodontal diseases such as Bacteroides gingivalis (patent document 3). In this method, ALP collected from saliva and others is heat-treated to remove ALP derived from the patient's cells; thus, only bacteria-derived ALP is specifically measured.
Patent document 1: Japanese Published Unexamined Patent Application No. S60-222768
Patent document 2: Japanese Translation of International Application (Kohyo) No. H3-501447
Patent document 3: Japanese Published Unexamined Patent Application No. H5-176796